It is standard practice in large civil-engineering projects to mix concrete at the site. The cement, water, and aggregates are stocked in bulk so they can be mixed together and loaded into standard mixer trucks which transport the mixture to the work location. This is, for instance, the procedure used on remote highway-construction projects. Such a procedure ensures that fresh concrete whose composition is closely controlled can be produced cheaply and delivered to the job without appreciable supply problems.
To this end a large mobile apparatus is used which usually comprises a tower that is transported to the site horizontally and erected, then fitted with various cranes, outrigger arms, and the like. The assembly must normally have devices for holding or amassing the various components of the concrete mixture, then lifting up this mixture to a level high enough, typically at least 4 meters, to load it into the cement truck.
Such an arrangement is usually very complex to set up. The assembly must normally be done by a special crew using a small crane, and even so quite some time is needed. Disassembly and preparation for transport to another site is normally also quite complex, necessitating a specially outfitted truck.